Vitamin D Supplements – Necessary Or Not?
With winter and short days with little sunlight upon us, the supplement industry is busy telling us we need to supplement vitamin D or run the risk of dire consequences. But what does vitamin D do and how much of it do you really need?
What Is Vitamin D?
Vitamin D belongs to the family of fat-soluble vitamins and plays its biggest role in the human metabolism by keeping a check on how much calcium and phosphorus is in your blood and how much especially of the former is absorbed in the gut. As calcium helps developing and maintaining strong bones, vitamin D therefore is often used together with calcium to increase bone density and to lighten fractures.
Lately vitamin D has also been connected to helping against hypertension (high blood pressure), osteoporosis (brittling of the bones), cancer, and various other diseases, but the jury is still out on if it really has an effect on these and how big it may be.
There are a number of food sources containing vitamin D in higher amounts (eg. beef liver, whole eggs, fish), but it can also be formed by simply exposing your skin to the sun, which is where we usually get the highest amounts from.
The Sunshine Vitamin
Which leads us to the hook supplement companies aim for to sell us vitamin D supplements with. In line with the old school of supplement marketing, vitamin D sellers grasp any slight evidence for vitamin D doing anything to something (see above) and claim it’s a reason to watch out for how much vitamin D we are getting. Then we are breathlessly told how dire the risk of us running into vitamin D deficiency is, especially during winter. To make sure we get the hint, they finally don’t fail to mention that those of us with office jobs supposedly don’t even get enough of vitamin D during summer. Because we are indoors most of the time and vitamin D can’t be synthesized from sunshine that hits your skin through glass (which actually is true).
All this of course contrary to our ancestors, who supposedly were more “connected to nature” and “sensed” how important it is to toil away in the great outdoors. It is, I suppose, food supplement marketing 101 to mention the wisdom of our forefathers at some point to sell stuff , despite our ancestors being people who on average only had a life expectancy half as long as what we enjoy today and mostly thought that what couldn’t be cured by bloodletting and emetics was uncurable.
How Much And Where From?
The truth about vitamin D is much more complicated. Half an hour exposure to sunlight during the summer, just showing the world your bare arms and face, forms about 10,000 IU (“international units”) of vitamin D, or about 250 mcg (microgram). Which is an awful lot when we read that according to the Office of Dietary Supplements (ODS), the recommended daily allowance (RDA) for vitamin D for adults is just 600 IU (15 mcg).
The problem now is that how much we get from the bright, big ball in the sky can vary by huge amounts. On cloudy days those 10,000 IU normally gotten within thirty minutes are about halved. Another 60% are lost if you live in a city full of smog or have a darker complexion. And if you apply a sun screen with a protection factor higher than 7 or if you are black, you will synthesize very little vitamin D. Not to mention that too much exposure to sunlight plays a big role in skin cancer and risking that to get enough vitamin D isn’t that swell an idea either.
On the other hand, in the US, and again according to the ODS, males consume to 204 to 288 IU per day from their nutrition, females 144 to 276 IU, therefore getting about half their RDA that way. This is not due to a so far secret love Americans have for beef liver, but to many foods in the US being fortified with vitamin D. In Europe vitamin D fortification is almost unheard of and deficiencies therefore potentially more likely.
The Big Ole Recommendation
As stated above, vitamin D is a fat-soluble vitamin and if you read my article on the different vitamins then you know that overdosing those generally is not a good idea. For vitamin D the maximum amount is still hotly debated, even though the ODS currently states the maximum daily amount you should have as 4,000 IU. That is a bit absurd, if just half an hour of sunlight generates 10,000 IU. If already 4,000 qualify as maximum, then at least in the southern US and southern Europe, where people during the summer spend way more time in direct sunlight, we should yearly see hundreds of cases of acute vitamin D overdoses.
The numbers at which the symptoms of vitamin D deficiency occur are established a bit better, and we can therefore use those as a guide. If you are an adult and live in the northern US or Canada, a vitamin D supplement containing 1,000 IU every second or third day during the winter should about cover your needs. In northern Europe, where food usually isn’t fortified, the same amount every day or every second during winter should do the same.
Yes, I did recommend usage of a vitamin supplement, but only with caution and pertaining to specific circumstances under which it may prove useful. Do keep in mind that this indeed is just a recommendation and various factors play a role in how much vitamin D is needed and safe for you to supplement. If you are in doubt and want to find out for sure how much you need, you should get your vitamin D level checked by your doctor.
Pictures courtesy of “barockschloss” and “Dahl-Face Photography“.
8 Comments
Vitamin D appears to be an interesting case in terms of toxicity. I’ve read before that although exposure to high levels of Vitamin D (i.e. like you say with 10,000 IU) appears to provoke no visibly negative symptoms. They also concluded that despite this, it is highly recommended not to go past a basic threshold as consumption beyond necessity has proven quite disastrous for for many other vitamins and supplements.
Yep, when I set out writing this, I figured it would be a straightforward affair. Then I learned about the entire discussion that entirely goes on about the RDA and the UL.
Neither of these are set in stone – it seems more like the current numbers were used to just have some that can be communicated.
I do not take nor recommend Vit D supplementation at this point. Vit D is the flavor of the month with vitamins so I’m waiting this one out. I do feel that some sun exposure is the best way to do it, but not too much sun as the risks of skin cancer are very real.
It took me a while to decide to write a recommendation, as I pretty much feel the same way about it you do.
However, it seems that light vitamin D supplementation is fairly safe and the amounts gotten from food rather low. The megadosages found in many of the available pills (most often 3,000 or 5,000 IU) are of course overkill.
I don’t take it but I have friends who do. 🙂
I am not a supplement person but I also live in a sunny climate and probably get enough Vitamin D from the sun. But then I have to wear sunscreen too – it’s so complicated!
That, in essence, summarizes it! 🙂
Hi, I have no quibble with the thinking re vitamin D. It is used to supplement some foods here in the UK, at least, even if not in other parts of Europe. This is because of the history of “smog” in industrial towns and cities and esp. in London, before the enacting of various “Clean Air Acts” to cut pollution. Rickets was a severe problem. This was eradicated many years ago, but sadly seems to be returning, dispite much cleaner air. Whether this is due to poor diet or because children rarely play outside with friends anymore, even in summer, is not yet clear.
What I wish to comment on is that this site rightly points out that we must not mistake correlation for causation or misinterpret science or data, but when talking about the health or not of our ancestors, the article refers to their average life span being half as long as ours. This is unhelpful as it tells us nothing about maximum life span, nor, in the absence of other data, cause of death or the health of the population generally. The media regularly point to the shorter life spans of people from times past, without making it clear that the data refers to “average” life spans and not total length of life.
This can mislead even trained experts, thus archaeologists excavating a crypt in London containing bodies buried in the 18th century were completely surprised to find a large number of burials recording deaths in the late 70s and above. This was a family tomb and mainly contained adult bodies. The average life span of the time WAS much lower, but this was due to the massive infant mortality and death due to illness or accident in childhood or early maturity. If a person survived their early years and had access to a good diet there was no reason for them not to live to old age.
It is not true, therefore, to say, as is often stated, that people aged 35 or 40 were “old”. Indeed, in the absence of refined sugar many people had better teeth than modern populations. I would also expect many people to have better bone density, not simply because of exposure to vitamin D, but because of a more active lifestyle, where almost all activity depended upon human or animal muscle. Only the very wealthy could afford to have slaves or servants do work for them.
Even in the late Victorian period, “average” life span was relatively low, but this is because of the huge numbers of infant deaths, up to 50% I believe. Adult life expectancy appears to have improved and adult mortality was much lower, barring accident or untreatable disease. Indeed, we forget how much difference antibiotics made in the treatment of otherwise fatal diseases.
In the same way, average life expectancy during 1914-1918 or 1939-1945 in Britain would be low, but not because of poor diet.
On the other hand, I admit that studies of very ancient skeletal remains indicate that age of death was, indeed, in the mid 30s. But, even if the sample sizes are big enough to extrapolate to the entire human population of the time, this would still only be relevant to the discussion of vitamin D and sunlight or to a discussion of diet if it could be shown that these deaths were not due to violence or to some epidemic and were typical of most of the population. If most people died because of illness or violence or because they were no longer able to avoid predators or enemies, their age at death would tell us very little about the virtues of sunlight or vitamin supplementation. What is needed is research into their diet and the presence or absence of deficiency disorders and diseases.
A final point that might be raised is that we know that much longer life spans are not simply a modern phenomenon. There may be more old people today, but old age, even extreme old age, did occur in agricultural societies in the distant past. Nevertheless, “average” life span has tended to increase as we move through time and into the modern period. If life expectancy is strongly linked to diet, this increase through time might suggest that Paleodiets are actually less healthy than modern diets. But such a conclusion requires more than anecdotal comments about “average” lifespans.
You are right, infant deaths pulled the average age of death down. However, even when that is accounted for, it is much lower than today.